<template>
  <div class="star" :class="starType">
    <span v-for="(itemClass, index) in itemClasses" :key="index" :class="itemClass" class="star-item"></span>
  </div>
</template>

<script>
const LENGTH = "5",
      CLS_ON = "on",
      CLS_OFF = "off",
      CLS_HALF = "half";
  export default {
    props: {
      size: Number,
      score: Number
    },
    computed: {
      starType() {
        return 'star-' + this.size;
      },
      itemClasses() {
        let result = [];
        let score = Math.floor(this.score * 2) / 2;
        let hasDecimal = score % 1 !== 0;
        let integer = Math.floor(score);
        for(let i = 0; i < integer; i ++){
          result.push(CLS_ON);
        }
        if(hasDecimal) {
          result.push(CLS_HALF);
        }
        while (result.length < LENGTH) {
          result.push(CLS_OFF);
        }
        return result;
      }
    }
  };
</script>

<style lang="less" scoped>
  .star {
    font-size: 0;
    .star-item {
      display: inline-block;
      background: no-repeat;
    }
  }
  .star-36 {
    .star-item {
      width: 15px;
      height: 15px;
      margin-right: 6px;
      background-size: 15px 15px;
    }
    :last-child {
      margin-right: 0;
    }
    .on {
      background-image: url('./images/star36_on@3x.png');
    }
    .half {
      background-image: url('./images/star36_half@3x.png');
    }
    .off {
      background-image: url('./images/star36_off@3x.png');
    }
  }
  .star-48 {
    .star-item {
      width: 20px;
      height: 20px;
      margin-right: 16px;
      background-size: 20px 20px;
    }
    :last-child {
      margin-right: 0;
    }
    .on {
      background-image: url('./images/star48_on@3x.png');
    }
    .half {
      background-image: url('./images/star48_half@3x.png');
    }
    .off {
      background-image: url('./images/star48_off@3x.png');
    }
  }
  .star-24 {
    .star-item {
      width: 10px;
      height: 10px;
      margin-right: 3px;
      background-size: 10px 10px;
    }
    :last-child {
      margin-right: 0;
    }
    .on {
      background-image: url('./images/star24_on@3x.png');
    }
    .half {
      background-image: url('./images/star24_half@3x.png');
    }
    .off {
      background-image: url('./images/star24_off@3x.png');
    }
  }
</style>